1. Field of the Invention
This invention relates to a radio communication device, a radio communication method and a radio communication program, and more particularly relates to radio communication devices which share a particular frequency band and constitute a plurality of radio communication systems, a radio communication method which controls operations of the radio communication systems, and a radio communication program which is applied to execute the foregoing method.
2. Description of the Related Art
There are communication devices which share a particular frequency band in a radio communication system, and a radio communication method which controls operations of the radio communication system, as described by Mitola (J. Mitola III, “Cognitive Radio for Flexible Mobile Multimedia Radio Communications”, IEEE Six International Workshop on Mobile Multimedia Radio communications (MoMuC99), pp. 3-10, November 1999). Mitola teaches that a low-priority communication device detects carriers in a common frequency band, and transmit signals when a high-priority communication device is not using the common frequency band.
Further, JP-A 2004-336387 discloses a technique which can protect one radio communication system against interference from other radio communication systems operating on a frequency band which is the same as that of the foregoing communication system, and which can promote efficient use of a time-domain of entire radio communication systems.
With the foregoing radio communication systems, when detecting, based on a carrier sensing, a radio station which does not belong to a radio communication system of the base station, the base station allocates a dummy signal in an inter-frame space of the data signal transmission-reception frame. Therefore, the base station may adversely affect the reception or transmission of the data signal in other radio communication systems.
Further, since the dummy signal is allocated to the interregnum of the data signal transmission-reception frame, no data signals can be transmitted in other radio communication systems. This will lead to reduced utility efficiency of a shared frequency band.
The present invention has been contemplated in order to overcome problems of the related art, and is intended to provide a communication device, a radio communication method in which a plurality of communication systems share one frequency band, and one communication system does not interfere with radio communications of the other communication systems, and a radio communication program which is applied to carry out the radio communication.